This Program Project is designed to coordinate the research in rheumatic diseases within the Division of Clinical Immunology and Rheumatology. The laboratories devoted to biochemistry, immunopathology, immunophysiology and collagen structure will be coordinated in order to put into perspective new information as it relates directly to understanding disease processes. Specific areas of study involve the structure, conformation and biology of: (1) Immunoglobulins, with particular emphasis on IgM; (2) Complement, with particular emphasis on Clq; (3) Collagen structure of basement membranes. These studies on immunoglobulins relate to understanding specificity, the way in which they interact with complement, as well as the mechanism by which damage to target organs, i.e., basement membranes, occurs. The interrelationships of our studies clearly delineates the way in which macromolecular structure is important in understanding the processes by which damage to target organs takes place. In addition, these investigations form the framework around which all of our clinical research and patient care center. Questions arising from specific problems of patient care at the bedside are finally analyzed through the various approaches included in this Coordinate Study in Rheumatic Diseases.